Weanling male B6D2F1/J mice were fed either: 1) a 24 percent protein diet; 2) a 4 percent protein diet; or 3) a 24 percent protein diet intermittently (fed Monday, Thursday, and 8 hrs. on Friday). Protein and enzymatic activities as well as DNA were measured in homogenates and various cellular fractions of liver. Both types of dietary restriction result in low cellular protein levels. However the activities of the enzymes were not consistently low in dietarily restricted animals; most likely due to specific regulatory mechanisms influenced by dietary manipulations. Three groups of C57BL/6J male mice, age 30 days, 14 months, and 20 months were fed diets containing either an amount of vitamins recommended by the National Academy of Sciences-National Research Council, one-half this amount, four times this amount, or an amount of vitamins recommended by the American Institute of Nutrition. Mice, regardless of age, offered one-half the RDA of vitamins began to die within two months and all were dead within eight months from the initiation of the study. At present the data do not indicate any beneficial effects from increasing the vitamins in the diet to four times the RDA.